Grinding wheel

Abstract

To provide a grinding wheel in which clogging at the time of grinding is suppressed.SOLUTION: A grain milling wheel 1 is a grain milling wheel that performs grain milling on a cereal grain. The grain milling wheel 1 includes: a base metal 31; a nickel plating layer 43 for fixing an abrasive grain 41 to a surface of the base metal 31; and an oil-repellent coating layer 45 provided in an upper layer of the nickel plating layer 43.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a grinding wheel. [Background technology]

[0002] Whitening wheels using superabrasive grains such as diamond or CBN have been known as grinding wheels for grinding and removing the surface layer of granular food (see, for example, Patent Document 1 below). This type of whitening wheel has better thermal conductivity than general grinding wheels using ceramic abrasive grains or alumina abrasive grains, and therefore has the advantage of providing good whitening quality. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 5897301 Summary of the Invention [Problem to be solved by the invention]

[0004] When using this type of grain milling wheel to mill grains, bran tends to get stuck in the gaps between the abrasive grains on the milling wheel surface, resulting in clogging. The bran generated during milling contains oil, which easily adheres to and accumulates on the surface of the metal plating layer that secures the abrasive grains. The accumulation of bran reduces the amount of abrasive grain protrusion, resulting in a decrease in milling performance. Resolving this decrease in milling performance due to clogging requires maintenance of the milling machine, and more frequent maintenance increases the milling machine's maintenance costs. This same problem can occur not only in grain milling, but also in all grinding wheels used to grind the surface layers of granular foods. Therefore, the present invention aims to provide a grinding wheel that suppresses clogging during grinding. [Means for solving the problem]

[0005] The gist of the present invention lies in the following [1] to [6].

[0006] [1] A grinding wheel for grinding the surface of granular food, A grinding wheel comprising: a base metal; a metal plating layer for adhering abrasive grains to the surface of the base metal; and an oil-repellent coating layer provided on top of the metal plating layer.

[0007] [2] The coating layer is The grinding wheel according to [1], wherein the layer is a eutectic plating layer formed by codepositing oil-repellent fine particles.

[0008] [3] The grinding wheel according to [2], wherein the oil-repellent fine particles are fine particles made of polytetrafluoroethylene.

[0009] [4] The grinding wheel according to [2], wherein the oil-repellent fine particles are fine particles made of silicon carbide.

[0010] [5] The grinding wheel according to [1], wherein the coating layer is a DLC film.

[0011] [6] The grinding wheel according to any one of [1] to [5], wherein the food is grain.

[0012] [7] The grinding wheel according to any one of [1] to [5], wherein the food is rice. [Effects of the Invention]

[0013] According to the present invention, it is possible to provide a grinding wheel that suppresses clogging during grinding. [Brief explanation of the drawings]

[0014] [Figure 1] FIG. 1 is a cross-sectional view showing a circulating, vertical-type sake polishing machine to which a polishing wheel is applied. [Figure 2] FIG. 1 is a cross-sectional view of a whitening wheel. [Figure 3] FIG. 2 is an enlarged cross-sectional view of the surface of the whitening wheel. DETAILED DESCRIPTION OF THE INVENTION

[0015] An embodiment of a grinding wheel according to the present invention will be described in detail below with reference to the drawings. The grinding wheel 1 of this embodiment is intended to grind sake rice and to grind and remove the surface layer of the sake rice. In other words, the grinding wheel 1 is a polishing wheel that polishes sake rice. FIG. 1 is a cross-sectional view showing a circulating, vertical sake polishing machine 3 to which the polishing wheel 1 according to this embodiment is applied. The sake polishing machine 3 includes a rice polishing tank 5 in which rice grains to be polished are temporarily stored, and a polishing chamber 7 in which rice grains sent from the rice polishing tank 5 are polished. A flow rate adjustment unit 6 is provided at the bottom of the rice polishing tank 5 to adjust the flow rate of rice grains sent from the rice polishing tank 5 to the polishing chamber 7.

[0016] A polishing wheel 1 is disposed in the center of the polishing chamber 7. A drive mechanism (not shown) including a pulley 23 provided at the lower end of the rotary shaft 21 is connected to the rotary shaft 21 of the polishing wheel 1, and the drive mechanism causes the polishing wheel 1 to rotate about a vertical axis within the polishing chamber 7. Rice grains supplied to the polishing chamber 7 from the rice polishing tank 5 are ground (polished) by the abrasive grains on the surface of the rotating polishing wheel 1 as they pass through the gap between the inner wall surface of the polishing chamber 7 and the polishing wheel 1, and are ultimately discharged from the discharge outlet 7a of the polishing chamber 7. A valve 8 is provided at the discharge outlet 7a to adjust the discharge resistance of the rice grains.

[0017] Furthermore, the polishing wheel 1 is equipped with a koku section 9 that separates and removes rice bran from the rice grains polished in the polishing chamber 7, and an elevator 11 that transports the rice grains that have passed through the koku section 9 upward and returns them to the rice polishing tank 5. The rice grains discharged from the discharge outlet 7a of the polishing chamber 7 slide down the inclined koku section 9 to the bottom end of the elevator 11. The bottom of the koku section 9 is mesh-like, so the rice bran mixed in with the rice grains falls through the bottom of the koku section 9 into the rice bran recovery section 13 below.

[0018] The elevator 11 has a structure that includes, for example, an endless belt (not shown) that circulates between the upper and lower ends of the elevator 11, and a number of buckets (not shown) that are attached to the endless belt. Each bucket scoops up rice grains at the lower end of the elevator 11 and discharges the rice grains into a conveying path 15 that is connected to the upper end of the elevator 11. The downstream side of the conveying path 15 is connected to the upper end of the rice polishing tank 5, and the rice grains sent through the conveying path 15 are again stored in the rice polishing tank 5. In the sake brewing polishing machine 3, the rice grains are circulated in the order of the rice polishing tank 5, polishing chamber 7, mankoku section 9, elevator 11, and conveying path 15, as described above, until the desired polishing ratio is achieved.

[0019] Next, the whitening wheel 1 will be described in more detail with reference to Figures 2 and 3. Figure 2 is a cross-sectional view of the whitening wheel 1, and Figure 3 is an enlarged cross-sectional view showing the vicinity of the surface of the whitening wheel 1.

[0020] As shown in Figure 2, the polishing wheel 1 includes a cylindrical base metal 31. Two V-grooves 33 extending in the circumferential direction of rotation are formed on the outer peripheral surface of the base metal 31. The cylindrical opening at the upper end of the base metal 31 is closed by a conical guide member 35, and rice grains sent from the rice polishing tank 5 to the polishing chamber 7 are guided toward the outer peripheral surface of the base metal 31 by the guide member 35. The rotation axis 21 of the polishing wheel 1 extends downward from the guide member 35. Furthermore, the polishing wheel 1 includes an abrasive layer 37 provided on the outer surface of the base metal 31. The abrasive layer 37 is provided over the entire outer surface of the base metal 31, including the inner surfaces of the V-grooves 33.

[0021] As shown in FIG. 3 , the abrasive grain layer 37 includes abrasive grains 41, a nickel plating layer 43, and a coating layer 45. The abrasive grains 41 are fixed to the surface of the base metal 31 by the nickel plating layer 43. For example, diamond abrasive grains or CBN abrasive grains may be used as the abrasive grains 41. After the abrasive grains 41 are arranged on the surface of the base metal 31, electrolytic plating or electroless nickel plating is applied to the surface, whereby the abrasive grains 41 are fixed to the surface of the base metal 31 while being embedded in the nickel plating layer 43. Since a known method may be used for such a process (electrodeposition process, etc.), further detailed description will be omitted.

[0022] The coating layer 45 is an oil-repellent layer provided on the nickel plating layer 43. Specifically, the coating layer 45 is a eutectoid plating layer in which oil-repellent fine particles are co-deposited, i.e., a nickel plating layer in which the oil-repellent fine particles are uniformly contained. The oil-repellent fine particles are suspended in a plating solution, and nickel plating is further performed on the nickel plating layer 43, thereby forming the coating layer 45.

[0023] The oil-repellent fine particles may be, for example, fine particles made of polytetrafluoroethylene (PTFE), fine particles made of silicon carbide (SiC), etc. When a portion of the oil-repellent fine particles is evenly exposed on the surface of the coating layer 45, the surface of the coating layer 45 has oil repellency, and as a result, the coating layer 45 has oil repellency.

[0024] The particle diameter of the abrasive grains 41 is, for example, about 180 to 400 μm, and the thickness of the nickel plating layer 43 may be, for example, about 60% of the particle diameter of the abrasive grains 41. The thickness of the coating layer 45 is, for example, about 2 to 10 μm. The particle diameter of the oil-repellent fine particles is, for example, about 1 μm or less.

[0025] The effects of the polishing wheel 1 having the coating layer 45 described above will be explained below. Conventional polishing wheels of this type suffer from clogging, where rice bran gets stuck in the gaps between the abrasive grains. Rice bran, in particular, contains a lot of oil, so it easily adheres to the surface of the metal plating layer that secures the abrasive grains, easily causing clogging.

[0026] In contrast, in the polishing wheel 1, the coating layer 45 present on top of the nickel plating layer 43 is oil-repellent, so oily rice bran is less likely to adhere to the coating layer 45. As a result, rice bran is less likely to get stuck in the gaps between the abrasive grains 41, which means clogging is suppressed. This reduces the frequency of maintenance for the sake polishing machine 3, and as a result, the maintenance costs of the rice polishing machine can be reduced.

[0027] Polytetrafluoroethylene and silicon carbide are not only oil-repellent but also water-repellent. Therefore, when polytetrafluoroethylene or silicon carbide particles are used as the oil-repellent particles of coating layer 45, coating layer 45 has both oil-repellent and water-repellent properties. Therefore, adhesion of the moisture in rice bran to coating layer 45 is less likely to occur, and as a result, clogging of the whitening wheel 1 is less likely to occur.

[0028] In order for the coating layer 45 to fully exhibit the oil repellency as described above, it is preferable that a large amount of oil repellent fine particles be exposed on the surface of the coating layer 45. Therefore, for example, the volume fraction of the oil repellent fine particles contained in the coating layer 45 is preferably 3% or more, and more preferably 20% or more.

[0029] The present invention can be implemented in various forms, including the above-described embodiment, with various modifications and improvements based on the knowledge of those skilled in the art. Furthermore, it is also possible to configure modified examples by utilizing the technical matters described in the above-described embodiment. The configurations of the respective embodiments may be used in appropriate combination.

[0030] The coating layer 45 in the above embodiment may be a DLC (Diamond-Like Carbon) film instead of a eutectoid plating layer of polytetrafluoroethylene (PTFE), silicon carbide (SiC), etc. The DLC film may be formed by a known film formation method such as a CVD film formation method or a PVD film formation method.

[0031] While the above embodiment is directed to a polishing wheel 1 for a sake brewing polishing machine 3, the present invention can also be applied to polishing wheels for polishing not only sake rice but also rice for eating. The present invention can also be applied to polishing wheels for polishing not only rice but also other grains (e.g., barley, wheat, corn, etc.). In particular, the polishing wheel of the present invention can be suitably used when the grain to be polished is one that contains a large amount of oil in its surface layer. The present invention is not limited to polishing wheels for grains, but can also be applied to grinding wheels for grinding the surface layer of other granular foods (e.g., soybeans, coffee beans, etc.). In particular, the grinding wheel of the present invention can be suitably used when the food to be ground is one that contains a large amount of oil in its surface layer. [Explanation of symbols]

[0032] 1...whitening wheel (grinding wheel), 31...base metal, 41...abrasive grains, 43...nickel plating layer (metal plating layer), 45...coating layer.

Claims

1. A grinding wheel for grinding a surface layer of granular food, comprising: A grinding wheel comprising: a base metal; a metal plating layer for adhering abrasive grains to a surface of the base metal; and an oil-repellent coating layer provided on the upper layer of the metal plating layer.

2. The coating layer is 2. The grinding wheel according to claim 1, wherein the layer is a eutectoid plating layer formed by codepositing oil-repellent fine particles.

3. 3. The grinding wheel according to claim 2, wherein the oil-repellent fine particles are made of polytetrafluoroethylene.

4. 3. The grinding wheel according to claim 2, wherein the oil-repellent particles are silicon carbide particles.

5. The grinding wheel according to claim 1 , wherein the coating layer is a DLC film.

6. The grinding wheel according to any one of claims 1 to 5, wherein the food is a grain.

7. The grinding wheel according to any one of claims 1 to 5, wherein the food is rice.

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